IL22234A

IL22234A - Thermoplastic composition

Info

Publication number: IL22234A
Application number: IL22234A
Authority: IL
Original assignee: Houilleres Bassin Du Nord
Priority date: 1963-10-17
Filing date: 1964-10-12
Publication date: 1968-02-26
Also published as: LU47075A1; DE1250120B; BE653912A; FR1379756A; FR1406658A; CH442743A; GB1019786A; NL141224B; NL6412073A; US3355514A

Description

This invention relates to the stabilisation of polyoxymethylenes against degradation.

Polyoxymethylenes are a group of thermoplastic resins with very advantageous mechanical properties containing structural units of the formula:- C- 0 - CH2 -]n where n is an integer. These resin are however, subject to degradation, particularly under the influence of heat and the degradation processes may be divided up into three different groups :- a) Degradation of the chain ends with liberation of gaseous formaldehyde. To obviate this degradation which takes place largely under the influence of heat, it has been shown that the presence of an ether or ester group at the end of chain prevents this degradation; b) Oxidation of the chains: the polyoxymethylene chains are readily oxidisable and they may be protected from this by the addition of anti-oxidants to the compositions. These anti-oxidants generally contain phenolic or amino groups; c) Cleavage of the chains: the chains may cleave and then also liberate formaldehyde from the cleaved ends. To obviate this, it has been proposed to add "formaldehyde acceptors". The function of these additives is to prevent degradation of polyoxymethylenes during its processing in the hot state. These additives are used in conjunction with the anti-oxidants discussed above and together with ester or ether terminated chains.

Various additives have been proposed to prevent the degradation of the polyoxymethylenes, particularly as the diamide of malonic acid, polymethacrylic amides, methyl and methacrylic amide methacrylate copolymers, and polyamides of the type obtained by the condensation of the following amines and acids : 1,1,6,6 tetramethylhexamethylene diamine/adipic acid 2,11 diaminodecane/2-2-5-5 tetr'amethyladipic acid 2,5 dimethylpiperazine/glutaric acid 2,5 dimethylpiperazine/suberic acid bis-3 aminopropylether/adipic acid 38% polycaprolactam, 35% polyhexamethylene adipamide/ 27% polyhexamethylene sebacamide terpolymer.

However, these additives are not capable of being used widely unless they satisfy a number of conditions, viz : - the absence of toxicity; - a high insolubility in conventional solvents; more particularly water and stability in respect of hydrolysis ; - ease of use; in particular, an additive in an extremely divided form results in good easy homogenisation with the polyoxymethylene powder with little expense; and because of the good dispersion the finished articles tend to have no stains.

According to the present invention, we provide a thermoplastic composition which comprises a mixture of a polyoxymethylene and a polyesteramide. Preferably, the polyesteramide should constitute from 0.8 to 5% by weight on the polyoxymethylene. These polyesteramides are excellent "formaldehyde acceptors".

The production of polyesteramides is already polyesteramid.es, reference may be made to the "Journal of Polymer Science" 61, (1962), 353-359, J.L.R. Williams, Laakso and Contois L,E, The polyesteramide is formed by the reaction of a diacid with a diamine, amino acid or the corresponding lactams and a diol or aminoalcohol.

If the amount of polyesteramide used is less than 0.8%, the maximum effects of the polyesteramide are not obtained, and if used in excess of 5 , the mechanical properties of the final polymer may be impaired.

All the polyesteramides used according to the invention may contain aliphatic, aromatic or cycloalkane groups. The polyesteramides with a melting point between 120° and 230°C are the most advantageous.

According to one aspect of the invention, the polyesteramide contains groups derived from caprolactam. Such polyesteramides are produced by adding caprolactam to the reaction mixture from which the polyesteramide is to be obtained. These caprolactam-based polyesteramides are more easily dispersed and used in the polyoxymethylene , and furthermore, they also improve the injection and extrusion properties of the stabilised polyoxymethylene.

The most preferred polyesteramides are those having the formula : - £0C-R-C0NH-(CH2)m-H CO„-R-CO-O-C„CH2 n-0-CO_-E ' -C0NH-(CHd)p-NH Co-a-co-o- cti*)^- o-Jx where m, n, p_ are integers in the range of from 1 to 12 and.R is hydrocarbon radical, such as alkyl or phenyl groups; this radical may differ from one polymer chain to another, and x is an integer.

Of these polyesteramides the most favoured are a) m n = p = 6 b) m p = 6, n = 10 m P = 6 c) n 6 for one half of the long chain, and n 10 for the other half, substance (c) being a copolymer.

The preferred polyesteramides , may be prepared by transesterifying a diester-diamide of the formula with a glycol of formula H0-(GH2)n-0H in the presence of a transesterification catalyst.

The value of the number n may be varied within the polyesteramide molecule by suitable choice of the glycol. This transesterification process gives copolyme: with certain physical properties - more particularly the melting point - differing from one another as required.

The stabilised polyoxymethylenes not only have excellent stability but also a good surface gloss.

In order that the invention may be more fully understood, the following Examples are given by way of illustration only.

Example I ; The following reactants were heated together in a neutral atmosphere in a stainless-steel autoclave at temperatures of 270-290°C for 2-3 hours at a pressure of 18 kg/cm . After which the reaction was concluded in vacuo (0.5 mm Hg) for 1-2 hours and the product removed from the reactor. The ingredients 0.75 mole of hexane diammonium adipate 0.25 mole of adipic acid Ο.25 mole of ethylene glycol The resultant polyesteramide had the following characteristics : - Melting point - 220° to 222°C Intrinsic viscosity ^ 0.42.

Example II; Using the same procedure as in Example I, but with the following ingredients :- 0,65 mole of hexane diammonium adipate 0.35 mole of adipic acid 0.35 mole 1-6 hexanediol A polyesteramide having the following characteristics :- Melting point - 220°C Intrinsic viscosity ^ 0.45 was obtained.

Example III; Using the same procedure as in Example I, but with the following ingredients :- 0.75 mole of hexane diammonium adipate Ο.25 mole of adipic acid Ο.25 mole of 1-6 hexanediol A polyesteramide having the following characteristics :- Melting point - 220°-225°C Viscosity 0.42 was obtained.

Example IV; Using the same procedure as in Example I, but 0.75 mole of hexane diammonium adipate 0.25 mole of adipic acid Ο.25 mole of 1-10 decanediol A polyesteramide having the following characteristics :- Melting point - 225°C Viscosity ^ 0.62 was obtained.

Example V: Using the same- procedure as in Example I, "but with the following ingredients : - 1.1 mole of hexane diammonium adipate Ο.5 mole of adipic acid Ο.5 mole of ethyleneglycol 1.1 mole of caprolactam , A polyesteramide having the following characteristics Melting point - 180°C Viscosity ^ 0.42 was obtained.

Example VI: Using the same procedure as in Example I, but with the following ingredients :- 0.5 mole of hexane diammonium adipate 0,25 mole of adipic acid Ο.25 mole of 1-6 hexanediol 0,5 mole of caprolactam A polyesteramide having the following characteristics : - Melting point - 170°C Viscosity 0,39 Example VII; Using the same procedure as in Example I, hut with the following ingredients : - 1,1 mole of hexane diammonium adipate 0.5^ mole of adipic acid 0,5-4- mole of 1-10 decanediol 1.1 mole of caprolactam A polyesteramide having the following characteristics :- Melting point - 177-180°C Viscosity ^ 0,65 was' ohtained.

Example VIII: Using the same procedure as in Example I, but with the following ingredients : - 0,25 mole of hexane diammonium adipate 0,25 mole of adipic acid 0,25 mole of 1-6 hexanediol 1 mole of caprolactam A polyesteramide having the following characteristics :- Melting point - 130°C Viscosity ^ 0.41 was obtained.

Example IX; Using the same procedure as in Example I, but with the following ingredients :- 0.82 mole of adipic acid 0.82 mole of 1-6 hexanediol 4.6 mole of caprolactam Melting point - 162°-165°C Viscosity ^ 0,45 was obtained.

Example X; Using the same procedure as in Example I, hut with the following ingredients : - 1.1 mole of hexane diammonium adipate 0.54 mole of adipic acid 0.54 mole of 1-6 hexanediol 1.1 mole of aminocaproic acid A polyesteramide having the following characteristics :- Melting point - 185°C.

Viscosity ^ 0.48 was obtained.

Example XI: Using the same procedure as in Example I, but with the following ingredients : - 1.57 mole of hexane diammonium adipate 0.58 mole of adipic acid 0.58 mole of 1-10 decanediol 0.56 mole of aminocaproic acid A polyesteramide having the following characteristics :- Melting point - 220°C Viscosity ^ 0.60 was obtained.

Example XII: Using the same procedure as in Example I, but with the following ingredients : - 0.25 mole of hexane diammonium adipate 0.25 mole of adipic acid 0,25 mole of 1-4 cyclohexanedimethanol 1 mole of £ caprolactam polyesteramide having the following characteristics : - Melting point - 120°C Viscosity 0.42 was obtained.

Example XIII: Using the same procedure as in Example I, but with the following ingredients :- 0.75 mole of hexane diammonium adipate Ο.25 mole of adipic acid Ο.25 mole of 1-4 cyclohexanedimethanol A polyesteramide having the following characteristics :- Melting point - 210°G Viscosity ^ 0.44 was obtained.

Example XIV; Using the same procedure as in Example I, but with the following ingredients :- Ο.25 mole of hexane diammonium adipate Ο.25. mole of adipic acid 0,25 mole of 1-10 decanediol 1 mole of £ caprolactam A polyesteramide having the following characteristics : - Melting point - 150°C Example XV: Using the same procedure as in Example I, but with the following ingredients : - 0,25 mole of hexane diammonium adipate Ο.25 mole of hexane diammonium sebacate Ο.25 mole of 1-10 decanediol Ο.25 mole of adipic acid 0.5 mole of £ caprolactam A polyesterami.de having the following characteristics :- Melting point - 1 5°C Viscosity ^ 0.58 was obtained.

Example XVI: Using the same procedure as in Example I, but with the following ingredients : - 0.5 mole of hexane diammonium adipate Ο.25 mole of sebacic acid 0,25 mole of 1-10 decanediol 0.5. mole of , caprolactam A polyesteramide having the following characteristics : - Melting point - 15 °C Viscosity ^ 0.55 was obtained.

The various polyesteramides were used for the stabilisation of polyoxymethylenes in various proportions .

The polyoxymethylene used in these tests was prepared by irradiation and polymerisation of solid .

This polyoxymethylene was then treated in accordance with the process described in French Patent Specification No. 1 , 333 , 327. The polyoxymethylene thus treated has an intrinsic viscosity of = 0.6. 0.5% of 1-1 bis (4 , 2- hydroxy- -methyl tertiobutylphenyl) butane (a phenolic- type anti-oxidant) was then added to the composition.

To assess the stability of the final products the resin compositions were heated at 222°C for ·¾· hour, 1 hour and 2 hours respectively and the amount of product lost was determined at the end of each of these periods .

The following table shows the results with the various compounds obtained with the polyesteramides produced in each of the Examples.

Additive % of % loss % loss % loss ("by Example additive 222°C 222°C 222°C No.) added after after after min 60 min 120 min Control 0 2.7 6.8 23 Example I 1.5 0.4 1.2 5 Example II 1.5 0.9 2.5 7.1 Example III 1.5 0.8 2.3 7.0 Example IV 1.5 0.4 2.0 7.0 Example V 1.5 0.4 0.96 3.98 Example VI 1.5 0.53 1.4 6.0 2 0.34 1.2 5.12 Example VII 2 0.33 1.0 5.3 Example VIII 1.5 0.55 1.78 5.36 2 0.32 1.01 4.9 Example IX 2 0.76 1.94 6.8 Example X 1.5 0.39 1.42 6.7 2 0.3 1.2 5 Example XI 1.5 0.45 1.57 7.05 2 0.38 1.49 6.29 Example XII 2 0.35 1.3 5.5 Example XIII 2 0.4 1.45 6.9 Example XIV 2 0.42 1.65 7.5 Example XV 2 0.45 1.8 7.9 3 0.39 1.4 6.5 Example XVI 2 0.4 1.65 7.7 3 0.3 1.45 6.6 To assess the above results, the following tahle gives the values obtained under the same conditions with various known additives.

Additive % of % loss % loss % loss additive 222°C 222°C 222°C added after after after min 60 min 120 min Malonamide 2 1.2 4.1 13.1 Urea 2 1.3 5.1 15 Terpolymer : 38% polycaprolactam % polyhexamethylene adipamide/27% poly-hexamethylene-sebacamide 2 0.9 2.7 8.2 A comparison of these tables shows the superior results obtained with the polyesteramide additives.

Other tests were carried out with certain polyesteramides and the thermal stability of the polyoxymethylene compounds obtained was measured by the following test:- 0.2 g. of the product undergoing test (stabilised polyoxymethylene) was placed in a test-tube which was then fitted in the inner casing of a thermostatic jacket; this inner casing was 22 cm. long and had an inside diameter of 2.8 cm. The temperature of the jacket was set to 222°C by boiling methyl salicylate. During the measurement the test-tube containing the product (length 100 mm., outside diameter 10 mm., inside diameter 8 mm.), of pyrex glass, was held in a vertical position inside the jacket by a metal coil suspended from the jacket , plug, its bottom end being 2 cm. above the bottom of the casing. Half an hour after the test-tube had been fitted in the inner casing of the jacket the test-tube was withdrawn and the loss of weight was measured.

The loss per minute for 100 g. of the product was calculated and this calculated value S has been given below in Examples XVII to XXI for the various products under test.

The gloss of the final products obtained was also measured with a "Gardner Gloss Meter". This meter is specially designed for this purpose and complies with the American ASTM Standard D 523-53 T; the gloss was measured by this method at an incidence of 60° (B 60 value indicated below) and an incidence of ° (B 5 value below).

The polyoxymethylene treated in these Examples was the same as that treated in the above examples.

The anti-oxidant used was 0.5% of bis-[2-hydroxy-3-(methyl-2-cyclohexyl)-5-methylphenyl] methane.

In the following Examples a polyesteramide of the following formula was used:- £0C-R-C0NH-(CH ) - CH ) - H where R, m, n and p_ are as stated in the Examples.

Example XVII: The polyoxymethylene contained 1% of the polyesteramide where :- m = n = p = 6, and E is a para-disubstituted phenyl radical.

The following results were obtained :- S = 0.03 B 60 = 6,2 B 5 = 9.0 Example XVIII; Using the same treated polyoxymethylene containing 1.5% of polyesteramide wherei :- m = p = 6 = The following results were obtained :- S = 0.027 B 60 = 6.0 B 4-5 = 8.6.

Example XIX; Using the same treated polyoxymethylene containing 1.5% of a polyesteramide copolymer wherein :- m = p = 6 n = 6 n = 10 (half the total quantity of glycol was used with n =_6 and the other half with n = 10) and R is a para-disubstituted phenyl radical.

The following results were obtained :- S = 0.03 B 60 = 6.3 B -5 = 9.4·.

Example XX: The same polyoxymethylene was used with an addition of a polyesteramide obtained by the action of the following diesterdiamide on glycol :-C^-O-CO-(CH2)^-CO-WH-(CH2)2-NH-C0-(CH2^-COOC^ The melting point of this polyesteramide was 170°C and its viscosity was °· ·· The addition of 2% of this polyesteramide to the polyoxymethylene gave a composition with a loss at 222°C as follows :- After 30 minutes: 0.6% 60 " 1.9% » 120 " 8 % Example XXI: Using the same treated polyoxymethylene containing 1.5% of the polyamide formed by the terpolymer: 38% polycaprolactam, 35% polyhexamethylene adipamide/27% polyhexamethylene sebacimide, the following results were obtained S = 0.03 B 60 = 4.9 B 5 = 7.3.

The values for this latter example are similar to those given by commercial polyoxymethylene compositions.

Claims

particularly described and ascertained the nature of our said invention and in what manner the is to be we declare that what we claim A thermoplastic composition which comprises a mixture of a polyoaymethylene and from to by weight on the a A composition according to Claim 1 in which the o o polyesteramide has a melting point of from 120 to 230 A composition according to 1 or 2 in which the polyesteramide contains structural units derived from A composition according to Claim 1 or 2 in which the polyesteramide has the d p d n where a integers of from 1 to R and are hydrocarbon radicals and is A composition according to Claim 4 which R and are phenylene radicals and a and equal to 6 or and are equal to and is equal to A composition according to Claim 4 in which R and are phenylene radicals and are each equal to 6 and a equals 6 for one half of the ohain and 10 for the other A composition according to Claim 1 containing a polyesteramide whose preparation is described in any of Examples I to A according to

1. Claim 1 substantially as herein described in any of Examplee XVII to Dated this 11th day of S3 insufficientOCRQuality